While most philosophers agree that libertarian agency and naturalism are incompatible, few attempts have been offered to spell out in some detail just why this is the case. My purpose in this article is to fill this gap in the literature by expanding on and clarifying the connection between naturalism as it is widely understood today and the rejection of libertarian agency. To accomplish this end I begin by clarifying different forms of libertarian agency and identity the key philosophical components that constitute libertarian agency per se. Second, three different aspects of contemporary scientific naturalism are analyzed and the relations among them clarified: the naturalist epistemic attitude, etiology, and ontology. This is followed by a presentation of six arguments for the claim that libertarian agency should be rejected by advocates of scientific naturalism. Finally, I criticize a recent attempt by Randolf Clarke to reconcile libertarian agency and scientific naturalism